Project description:Oct4, a key transcription factor for maintaining the pluripotency and self-renewal of stem cells has been reported previously. It also plays an important role in tumor proliferation and apoptosis, but the role of Oct4 been in tumor metastasis is still not very clear. Here, we found that ectopic expression of Oct4 in breast cancer cells can inhibit their migration and invasion. Detailed examinations revealed that Oct4 up-regulates expression of E-cadherin, indicative of its inhibitory role in epithelial-mesenchymal transition (EMT). RNA-sequence assay showed that Oct4 down-regulates expression of Rnd1. As an atypical Rho protein, Rnd1 can affect cytoskeleton rearrangement and regulate cadherin-based cell-cell adhesion by antagonizing the typical Rho protein, RhoA. Ectopic expression of Rnd1 in MDA-MB-231 cells changes cell morphology which influences cell adhesion and increases migration. It is reported that EMT is accompanied by cytoskeleton remodeling, we hypothesized that Rnd1 may play a role in regulating EMT. Over-expression of Rnd1 can partly rescue the inhibitory effects induced by Oct4, not only migration and invasion, but also in E-cadherin level and cellular morphology. Furthermore, silencing of Rnd1 can up-regulate the expression of E-cadherin in MDA-MB-231 cells. These results present evidence that ectopic expression of Oct4 increases E-cadherin and inhibits metastasis, effects which may be related to Rnd1 associated cell-cell adhesion in breast cancer cells. Examination of mRNA profiles in MDA-MB-231 cells with OCT4 overexpressing

Project description:Glucocorticoids (GC) have been widely used as coadjuvants in the treatment of solid tumors, but GC treatment may be associated with poor pharmacotherapeutic response and/or prognosis. The genomic action of GC in these tumors is largely unknown. Here we find that dexamethasone (Dex, a synthetic GC) regulated genes in triple-negative breast cancer (TNBC) cells are associated with drug resistance. Importantly, these GC-regulated genes are aberrantly expressed in TNBC patients and associated with unfavorable clinical outcomes. Interestingly, in TNBC cells, Compound A (CpdA, a selective GR modulator) only regulates a small number of genes not involved in carcinogenesis and therapy resistance. Mechanistic studies using a ChIP-exo approach reveal that Dex- but not CpdA-liganded glucocorticoid receptor (GR) binds to a single glucocorticoid response element (GRE), which drives the expression of pro-tumorigenic genes. Our data suggest that development of safe coadjuvant therapy should consider the distinct genomic function between Dex- and CpdA-liganded GR. To study GR-regulated genes and define GRE in human genome, RNA-seq and GR ChIP-exo are performed in MDA-MB-231 cells before/after dex and CpdA stimulation. Each experiment includes two replicates.

Project description:Gene expression profiles were performed on MDA-MB-231 TNBC cell line treated with entinostast, all-trans retinoic acid (ATRA), and doxorubicin as single, double, and triple combinations using Illumina. Treatment signatures were made from each drug treatment and integrated to find a comprehensive view of changes associated with the epigenetic, differentiation and chemotherapy combination

Project description:Acquired drug resistance represents a major challenge in chemo-therapy treatment for various types of cancers. We have found that the retinoid X receptor–selective agonist bexarotene (LGD1069, Targretin) was efficacious in treating chemo-resistant cancer cells. The goal of this microarray study was to understand the mechanism of bexarotene’s role in overcoming acquired drug resistance using human breast cancer cells MDA-MB-231 as a model system and paclitaxel as model compound. After MDA-MB-231 cells were repeatedly treated with paclitaxel for 8 cycles with each cycle including a 3-day treatment with 30 nM paclitaxel and followed by a 7-day exposure to control medium, MDA cells resistant to paclitaxel were developed and their growth was no longer inhibited by paclitaxel treatment. Those MDA cells with acquired drug resistance, when treated with paclitaxel and bexarotene in combination, could regain their sensitivity and their growth were again inhibited. Therefore, RNA samples from parental MDA-MB-231 cells, paclitaxel-resistant MDA cells treated with vehicle, paclitaxel alone or in combination with bexarotene, were used for perform global gene expression profiling with Affymetrix HG-U133A gene chips. Keywords: Drug Treatment MDA-MB-231 cells were exposed to regimens on a 10-day cycle: a 3-day treatment with 30 nM paclitaxel and followed by a 7-day exposure to control medium. Paclitaxel resistant MDA-MB-231 cells (MDA-PR) were established within 8 cycles of such treatment (80 days). These MDA-PR cells were then treated with vehicle control, paclitaxel along, or the combination of 30 nM paclitaxel ( 3 days on and 7 days off) and 1 µM Targretin (10 days on) in a new 10-day cycle for 3 months. Thus, there are four treatment groups, parent MDA cells, MDA-PR, MDA-PR treated with paclitaxel, MDA-PR treated with paclitaxel and bexarotene, and each group had four biological replicates.

Project description:To clarify and compare gene expression profile of each cell line, we have employed microarray expression profiling. The expression of many genes was similar in MM231-D3H2LN-GFP-BM2 cells parental cells, MM231-D3H2LN-GFP cells; however, the expression of genes related to the cell cycle was decreased in the BM2 cells compared with the parental cells. We also confirmed that the global gene expression patterns of the CD44+ and CD44- MM231-D3H2LN-GFP-BM2 cells were similar, although some genes which encode proteins that breast cancer cell dormancy, such as SRC and ERBB2 were increased and decreased, respectively, in the CD44- population. The gene expression of breast cancer cells metastatic to bone marrow and those with or without expression of cancer stem cell marker were measured.

Project description:RNA extraction and microarray analysis total RNA from immortalized normal mammary epithelial cells (184A1, MCF-12A), breast cancer cells (MDA-MB-231, MCF-7, MDA-MB-468, SK-BR-3), BCSC (MDA-MB-231SC, MCF-7SC, XM322, XM607). MDA-MB-231SC and MCF-7SC originating from breast cancer cell lines; XM322 and XM607 derived from clinical specimens which had been described in previous submission (E-MTAB-5057). The miRNA profiling was performed using Agilent miRNA array. Microarray experiments were conducted according to the manufacturer's instructions. To select the differentially expressed genes, we used threshold values of ≥ 2 and ≤ −2-fold change and a Benjamini-Hochberg corrected p value of 0.05. The data was Log2 transformed and median centered by genes using the Adjust Data function of Cluster 3.0 software then further analyzed with hierarchical clustering with average linkage (genes which value more than 100 were evaluated).

Project description:In order to study molecular changes in the stroma from tissue samples it is recommended to separate tumor tissue from stromal tissue. This is particularly relevant to mouse tumor xenograft models where tumor, particularly metastatic tumors, can be small and difficult to separate from the host tissue. In our research we compared qualitatively the ability of high-throughput mRNA sequencing, RNA-Seq, and microarrays to detect tumor (human) and stromal (mouse) expression from mixed tumor-stromal samples in terms of the genes and pathways that are involved in cross-alignment (RNA-Seq) and cross-hybridization (microarrays). Human samples consisted of total RNA obtained from MDA-MB-231 human breast carcinoma cell line and isolated from three independent cultures of sub-confluent MDA-MB-231 cell lines in exponential phase of growth. Mouse samples were obtained from NOD scid gamma mice, and normal lung tissue was harvested from three independent age-matched mice.